A support for a MTC-capable UE in a LTE network is gaining attention because integrating the MTC capabilities into a LTE network has an advantage of supporting two widely deployed network devices in a single network. A low-cost solution may involve using only single receiving RF chain because it may significantly lower the costs of LTE MTC devices. It is known that there will likely be about 3 dB coverage loss with single receiver RF chain compared to regular LTE UEs. So a solution to compensate for control signaling coverage loss due to use of a single receiving RF chain is needed.
Some of the proposed solutions to the issue of control signaling coverage loss may require either an increased densification of sites or remedial solutions at the receiver such as small home area networks, meshes, or external antennas with additional antenna feeds. These solutions may be impractical, require additional spectrum, and lead to higher cost. Therefore a coverage improvement solution is desirable that can meet the lost-cost requirement of MTC-capable devices such as smart-metering devices, while utilizing LTE sites and RF hardware, and efficiently sharing the same spectrum/carrier as LTE to reduce costs for network deployment.
A signaling coverage improvement may involve downlink control channel coverage improvement because downlink control signaling is the bottleneck of the LTE in downlink coverage. A downlink control signaling is located at the start of each downlink subframe up to the first three OFDM symbols. Downlink control signaling may be carried by a Physical Downlink Control Channel (PDCCH) which may carry DL scheduling assignment and uplink scheduling grants. Thus, there is a need to extend the PDCCH signaling channel to support MTC-capable UEs.
The following abbreviations are used in this application.    A/N Acknowledge/Non-Acknowledge    BS Base Station    CCE control channel element    CSS Common Search Space    DL Downlink    ePDCCH enhanced Physical Downlink Control Channel    eNB Enhanced Node B. Name for Node B in LTE    FDM Frequency Domain Multiplexing    HARQ Hybrid Adaptive Repeat and Request    LTE Long Term Evolution    LTE-A Long Term Evolution Advanced    M-ePDCCH MTC-capable extended PDCCH    M-PDCCH MTC-capable PDCCH    MIB Master Information Block    MTC Machine Type Communication    NCT New Carrier Type    OS OFDM Symbol    PDCCH Physical Downlink Control Channel    PDSCH Physical Downlink Shared Channel    RF Radio Frequency    RRC Radio Resource Control    SIB1 System Information Blocks    USS User Search Space    TA Timing Advance    UE User Equipment    UL Uplink    UMTS Universal Mobile Telecommunications System    UTRAN UMTS Radio Access Network    WCDMA Wideband Code Division Multiple Access